Question

A tap can fill a tank in 36 minutes and another can empty it in 18 minutes. If the tank is already half full and both the taps are opened together, the tank will be:
A) Filled in 9 minutes
B) Filled in 18 minutes
C) Emptied in 12 minutes
D) Emptied in 18 minutes

Answer 1

Answer:

The tank will be emptied in 18 minutes.

Step-by-step explanation:

Given that a tank is filled in 36 mins.

Thus, in one minute the tap can fill 1/36 of the tank.

Similarly, in one minute, 1/18 can be emptied.

If each of the taps is open simultaneously, the net part of the tank emptied in a single minute can be calculated as follows.

1/18 - 1/36 = 1/36

The full tank will be emptied by them in 36 minutes.

Therefore, to empty half of the tank takes 18 minutes.

#SPJ2

Answer 2

Answer:

The answer is option D Emptied in 18 minutes

Step-by-step explanation:

According to question
tap 1 can fill a tank in 36 minutes hence in 1 minute it can fill $\frac{1}{36}$ of the tank while tap 2 can empty a tank in 18 minutes so in 1 minute it can empty $\frac{1}{18}$ of the tank.
Since the tank is half full it must would have taaken half the total time to fill it that is 18 minutes so in 1 minute $\frac{1}{18}$ of the tank fills and can take 9 minutes to be emptied so in 1 minute $\frac{1}{9}$ of the tank is empties
So if both the taps are opened simultaneously then in 1 minute
$\frac{1}{9} - \frac{1}{18} = \frac{1}{18} .$ of the tank empties.
Hence it will take 18 minutes for the tank to be empty.